Effects of aspirin, naloxone and placebo.

This study was designed to examine the effects of aspirin, naloxone and placebo treatment on serum beta-endorphin concentration and joint pain in patients with rheumatoid arthritis (RA). Ten patients with definite or classical RA were studied. All treatments were administered in a randomized sequence. On each study day, the following measurements were carried out at specified time intervals: serum beta-endorphin concentration, serum salicylate concentration and joint pain score on a visual analogue horizontal scale. We conclude that in patients with rheumatoid arthritis suffering from chronic joint pain, serum beta-endorphin does not appear to play a role in pain relief.